For the discharge of media, particularly pharmaceutical or cosmetic products, numerous types of dispensers have been developed, e.g. atomizers or sprayers. They normally operate with manual drive for a pump plunger or piston, which places the medium under the pressure necessary for discharge purposes. Particularly for very expensive pharmaceuticals which have to be very accurately dosed disposable dosing means have been developed, in which the container for the medium is simultaneously the pump chamber and container closure of the pump plunger. Such an atomizer is known from DE-A-44 12 041. For manual drive purposes the medium container is received in a jacket on which the user presses and directly mechanically moves the pump plunger.
The cooperation of the manual drive with the specific discharge function, e.g. an atomization, is not ensured under all circumstances. It is consequently necessary to ensure that the user acts with a relatively uniform pressure over the entire plunger stroke in order to ensure a reliable, uniform atomization. Particularly for such disposable dosing means, it would also be appropriate to reduce the number of moving parts and their manufacturing requirements.
For the discharge of pasty products, e.g. toothpaste, it is known to use containers with a separating plunger running therein (DE 44 20 594 A; DE 82 22 355 U; U.S. Pat. No. 3,184,120 A; DE 43 08 397 A; DE 82 20 965 U). They are partly driven by air pressure.
Thus, the object of the invention is to provide a dispenser for flowable media, particularly for atomizing liquids which, in the case of simple construction and operation, creates the prerequisites for a uniform medium discharge. On the medium chamber simultaneously forming the pump chamber it can have a partly compressible pressure chamber, which is filled with a pressure fluid, preferably a liquid, e.g. water and which simultaneously places under pressure the pump plunger serving as the medium chamber closure.
As a certain minimum pressure is necessary for effective atomization, it must be ensured that this is maintained from the start to the finish of the discharge process. For this purpose in the inoperative state the plunger can have a predetermined restraint, which must be overcome in order to move the plunger, whilst the running resistance for continuing the discharge process can be reduced. This can be brought about by a corresponding choice of materials for the plunger and medium chamber wall, as well as the pressure between the plunger and medium chamber wall. However, it is also possible to incorporate certain mechanical restraints, e.g. a circumferential rib in the medium chamber wall, a snap action device, etc.
Apart from liquids, the pressure fluid can be constituted by other flowable media, e.g. gases such as air and which as a result of their compressibility do not permit such a direct transfer of forces as liquids, but as a result of said compressibility form a hydraulic accumulator which, after overcoming the static friction of the plunger, ensure a complete and speedy performance of the stroke, i.e. a pressure point function in the manner described hereinbefore.
For the operation of the dispenser the invention makes it possible to effect a hydraulic transmission. For this purpose the plunger has different active surfaces for the medium and pressure chambers. With a relatively low pressure in the pressure chamber it is possible to produce a correspondingly higher pressure in the medium chamber.
In order to ensure an adequate initial pressure the pressure chamber can have a manually operable snap action device. It is possible, e.g. through the curvature of the wall of the pressure chamber, to obtain the action of a xe2x80x9csnap catchxe2x80x9d. This can be used for producing a very brief, sudden discharge process. It is also possible to select the pressure fluid as a combination of compressible and incompressible media, in that e.g. a certain gas volume (air pocket) is incorporated into a liquid. If e.g. as a result of a xe2x80x9csnap catch actionxe2x80x9d a sudden pressure build-up is obtained in the pressure chamber, this can be substantially maintained over the in some cases somewhat longer discharge stroke.
The pressure chamber can be constructed in the manner of a squeezing container and is preferably directly connected to the medium chamber. It is e.g. possible to construct the medium chamber as a somewhat thicker walled cylinder and to connect to it a thinner walled jacket as the pressure chamber and which after filling the medium chamber with the medium to be discharged, inserting the plunger and filling the pressure chamber with the pressure fluid is sealed e.g. by a weld. As a result the dispenser can be made from a very few parts, namely a base part forming the medium and pressure chambers, the plunger and optionally an insert in the medium chamber, which cooperates with the outlet port for forming an atomizing nozzle.
It is advantageous to manufacture the base part by two-component injection moulding, in which simultaneously or successively different plastics or plastic variants for different areas of the shaped body are injected into the injection mould. Thus, the cylinder section can comprise a more rigid and more shape-stable plastic, whereas a softer, more flexible plastic is chosen for the pressure chamber section. Advantageously both should be of the same plastic type, but with a different hardness setting, in order to permit type-pure disposal. This is always possible in the case of the invention due to the lack of other materials such as metals or the like.
The discharge port can be closed by valves, which can be either pressure-operated or path-operated. However, it is adequate for disposable dosing means to close or seal the discharge port, which can simultaneously form an atomizing nozzle, with a break-off closure.
It is consequently possible to manufacture a dispenser having a very simple construction. It is even possible to manufacture it in the form of a strip of several continuous dispensers, which are interconnected by means of a predetermined breaking point at their base parts. This facilitates not only manufacture and transportation in the filling means, but also makes it possible to pack together several pharmaceutical charges, from which an individual charge can then be broken off.
These and other features can be gathered from the claims, description and drawings and the individual features, both singly and in the form of subcombinations, can be implemented in an embodiment of the invention and in other fields and can represent advantageous, independently protectable constructions for which protection is hereby claimed. The subdivision of the application into individual sections and the subtitles in no way restrict the general validity of the statements made thereunder.